1. Field of the Invention (Technical Field)
The present invention relates to unobtrusive methods and apparatuses for detecting changes in a scene.
2. Description of Related Art
Security, surveillance, and defense systems use imaging sensors to monitor unattended areas for evidence of unauthorized access, theft, tampering, and placement of bombs or other undesirable devices. It is most desirable to have such a surveillance system be capable of identifying threats without man-in-the-loop monitoring.
Current systems to detect changes in imagery employ storage of the previous images. The new data is then compared to the stored data using an intensive processing system. The two sets of imagery are digitized, and loaded into memory. Multiple frames are stitched together into a super-frame of data. The algorithm then looks for recognizable features in the scenery. These features are used as anchor points to register the two sets of data properly so as to reduce the rate of false alarms. Then, each pixel is subtracted from the corresponding, re-registered pixel in the older data set.
The present invention is of a material and method of use that drastically reduces the amount of computation needed to determine scene changes. One application for the present invention is in the monitoring of roadside guardrails and debris piles in Iraq, where Improvised Explosive Devices (IEDs) are being placed. A second potential use for the material of the invention is as an optical marker tag on vehicles suspected of containing car-bombs. Classical architectures for this require extensive processing power and time to reduce the data. The effectiveness of these systems will be greatly enhanced by the ability to identify specific areas of the imagery where something has changed recently.